"Trusts based models, are solution to overcome the passive insider attacks and are used to enhance the cooperative routing in MANET. Trust based models calculate the trust value of neighbor nodes in two ways, viz., direct trust and indirect trust (recommendation trust). Direct trust value is calculated by observing the behavior of the neighbor node directly in terms of the packet forwarding ratio, the indirect trust value of a node is calculated using the recommendation received from neighbor nodes. However, some adversaries perform badmouthing attack (Slandering attack), selective behavior attack, and Sybil attack by sending dishonest recommendations."